#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#include <assert.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <errno.h>
#include "thread_pool.h"

//创建线程池
threadpool_t *threadpool_create(int min_thr_num, int max_thr_num, int queue_max_size)
{
	threadpool_t *pool = NULL;
	int i;
	
	do{
		if((pool = (threadpool_t *)malloc(sizeof(threadpool_t))) == NULL)
		{
			printf("malloc threadpool fail");
			break;
		}
		pool->min_thr_num = min_thr_num;
		pool->max_thr_num = max_thr_num;
		pool->busy_thr_num = 0;
		pool->live_thr_num = min_thr_num;
		pool->queue_size = 0;
		pool->queue_max_size = queue_max_size;
		pool->queue_front = 0;
		pool->queue_rear = 0;
		pool->shutdown = 0;
		pool->threads = (pthread_t *)malloc(sizeof(pthread_t)*max_thr_num);
		if (pool->threads == NULL)
		{
			printf("malloc threads fail");
			break;
		}
		memset(pool->threads, 0, sizeof(pool->threads));
		pool->task_queue = (threadpool_task_t *)malloc(sizeof(threadpool_task_t)*queue_max_size);
		if (pool->task_queue == NULL)
		{
			printf("malloc task_queue fail");
			break;
		}
		if (pthread_mutex_init(&(pool->lock), NULL) != 0
		|| pthread_mutex_init(&(pool->thread_counter), NULL) != 0
		|| pthread_cond_init(&(pool->queue_not_empty), NULL) != 0
		|| pthread_cond_init(&(pool->queue_not_full), NULL) != 0)
		{
			printf("init the lock or cond fail");
			break;
		}
		 /**
		 * start work thread min_thr_num
		 */
		for(i = 0; i < min_thr_num; i++)
		{
			//启动任务线程
			pthread_create(&(pool->threads[i]), NULL, threadpool_thread, (void *)pool);
			//printf("start thread 0x%x...\n", pool->threads[i]);
		}
		//启动管理线程
		pthread_create(&(pool->adjust_tid), NULL, adjust_thread, (void *)pool);
		return pool;
	 }while(0);
	threadpool_free(pool);
	return NULL;
}
//把任务添加到队列中
int threadpool_add(threadpool_t *pool, void*(*function)(void *arg), void *arg)
{
	assert(pool != NULL);
	assert(function != NULL);
	assert(arg != NULL);
	pthread_mutex_lock(&(pool->lock));
	//队列满的时候，等待
	while ((pool->queue_size == pool->queue_max_size) && (!pool->shutdown))
	{
		//queue full wait
		pthread_cond_wait(&(pool->queue_not_full), &(pool->lock));
	}
	if (pool->shutdown)
	{
		pthread_mutex_unlock(&(pool->lock));
	}
	//如下是添加任务到队列，使用循环队列
	if (pool->task_queue[pool->queue_rear].arg != NULL)
	{
		free(pool->task_queue[pool->queue_rear].arg);
		pool->task_queue[pool->queue_rear].arg = NULL;
	}
	pool->task_queue[pool->queue_rear].function = function;
	pool->task_queue[pool->queue_rear].arg = arg;
	pool->queue_rear = (pool->queue_rear + 1)%pool->queue_max_size;
	pool->queue_size++;
	//每次加完任务，发个信号给线程
	//若没有线程处于等待状态，此句则无效，但不影响
	pthread_cond_signal(&(pool->queue_not_empty));
	pthread_mutex_unlock(&(pool->lock));
	return 0;
}
//线程执行任务
void *threadpool_thread(void *threadpool)
{
	threadpool_t *pool = (threadpool_t *)threadpool;
	threadpool_task_t task;
	while(1)
	{
		/* Lock must be taken to wait on conditional variable */
		pthread_mutex_lock(&(pool->lock));
		//任务队列为空的时候，等待
		while ((pool->queue_size == 0) && (!pool->shutdown))
		{
			//printf("thread 0x%x is waiting\n", pthread_self());
			pthread_cond_wait(&(pool->queue_not_empty), &(pool->lock));
			//被唤醒后，判断是否是要退出的线程
			if (pool->wait_exit_thr_num > 0)
			{
				pool->wait_exit_thr_num--;
				if (pool->live_thr_num > pool->min_thr_num)
				{
					//printf("thread 0x%x is exiting\n", pthread_self());
					pool->live_thr_num--;
					pthread_mutex_unlock(&(pool->lock));
					pthread_exit(NULL);
				}
			}
		}
		if (pool->shutdown)
		{
			pthread_mutex_unlock(&(pool->lock));
			//printf("thread 0x%x is exiting\n", pthread_self());
			pthread_exit(NULL);
		}
		//get a task from queue
		task.function = pool->task_queue[pool->queue_front].function;
		task.arg = pool->task_queue[pool->queue_front].arg;
		pool->queue_front = (pool->queue_front + 1)%pool->queue_max_size;
		pool->queue_size--;
		//now queue must be not full
		pthread_cond_broadcast(&(pool->queue_not_full));
		pthread_mutex_unlock(&(pool->lock));
		// Get to work
		//printf("thread 0x%x start working\n", pthread_self());
		pthread_mutex_lock(&(pool->thread_counter));
		pool->busy_thr_num++;
		pthread_mutex_unlock(&(pool->thread_counter));
		(*(task.function))(task.arg);
		// task run over
		//printf("thread 0x%x end working\n", pthread_self());
		pthread_mutex_lock(&(pool->thread_counter));
		pool->busy_thr_num--;
		pthread_mutex_unlock(&(pool->thread_counter));
	}
	pthread_exit(NULL);
	return (NULL);
}
//管理线程
void *adjust_thread(void *threadpool)
{
	threadpool_t *pool = (threadpool_t *)threadpool;
	while (!pool->shutdown)
	{
		sleep(DEFAULT_TIME);
		pthread_mutex_lock(&(pool->lock));
		int queue_size = pool->queue_size;
		int live_thr_num = pool->live_thr_num;
		pthread_mutex_unlock(&(pool->lock));
		pthread_mutex_lock(&(pool->thread_counter));
		int busy_thr_num = pool->busy_thr_num;
		pthread_mutex_unlock(&(pool->thread_counter));
		//任务多线程少，增加线程
		if (queue_size >= MIN_WAIT_TASK_NUM
		&& live_thr_num < pool->max_thr_num)
		{
			//need add thread
			pthread_mutex_lock(&(pool->lock));
			int add = 0;
			int i;
			for (i = 0; i < pool->max_thr_num && add < DEFAULT_THREAD_VARY
			&& pool->live_thr_num < pool->max_thr_num; i++)
			{
				if (pool->threads[i] == 0 || !is_thread_alive(pool->threads[i]))
				{
					pthread_create(&(pool->threads[i]), NULL, threadpool_thread, (void *)pool);
					add++;
					pool->live_thr_num++;
				}
			}
			pthread_mutex_unlock(&(pool->lock));
		}
		//任务少线程多，减少线程
		if ((busy_thr_num * 2) < live_thr_num
		&& live_thr_num > pool->min_thr_num)
		{
			//need del thread
			pthread_mutex_lock(&(pool->lock));
			pool->wait_exit_thr_num = DEFAULT_THREAD_VARY;
			pthread_mutex_unlock(&(pool->lock));
			//wake up thread to exit
			int i;
			for (i = 0; i < DEFAULT_THREAD_VARY; i++)
			{
				pthread_cond_signal(&(pool->queue_not_empty));
			}
		}
	}
}
int threadpool_destroy(threadpool_t *pool)
{
	int i;
	if (pool == NULL)
	{
		return -1;
	}
	pool->shutdown = 1;
	//adjust_tid exit first
	pthread_join(pool->adjust_tid, NULL);
	// wake up the waiting thread
	pthread_cond_broadcast(&(pool->queue_not_empty));
	for (i = 0; i < pool->min_thr_num; i++)
	{
		pthread_join(pool->threads[i], NULL);
	}
	threadpool_free(pool);
	return 0;
}
int threadpool_free(threadpool_t *pool)
{
	if (pool == NULL)
	{
		return -1;
	}
	if (pool->task_queue)
	{
		free(pool->task_queue);
	}
	if (pool->threads)
	{
		free(pool->threads);
		pthread_mutex_lock(&(pool->lock));
		pthread_mutex_destroy(&(pool->lock));
		pthread_mutex_lock(&(pool->thread_counter));
		pthread_mutex_destroy(&(pool->thread_counter));
		pthread_cond_destroy(&(pool->queue_not_empty));
		pthread_cond_destroy(&(pool->queue_not_full));
	}
	free(pool);
	pool = NULL;
	return 0;
}
int threadpool_all_threadnum(threadpool_t *pool)
{
	int all_threadnum = -1;
	pthread_mutex_lock(&(pool->lock));
	all_threadnum = pool->live_thr_num;
	pthread_mutex_unlock(&(pool->lock));
	return all_threadnum;
}
int threadpool_busy_threadnum(threadpool_t *pool)
{
	int busy_threadnum = -1;
	pthread_mutex_lock(&(pool->thread_counter));
	busy_threadnum = pool->busy_thr_num;
	pthread_mutex_unlock(&(pool->thread_counter));
	return busy_threadnum;
}
int is_thread_alive(pthread_t tid)
{
	int kill_rc = pthread_kill(tid, 0);
	if (kill_rc == ESRCH)
	{
		return -1;
	}
	return 0;
}
// for test
//void *process(void *arg)
//{
//	printf("thread 0x%x working on task %d\n ",pthread_self(),*(int *)arg);
//	sleep(1);
//	printf("task %d is end\n",*(int *)arg);
//	return NULL;
//}
//int main()
//{
//	int i;
//	threadpool_t *thp = threadpool_create(3,100,12);
//	printf("pool inited");
//	
//	int *num = (int *)malloc(sizeof(int)*20);
//	for (i=0;i<10;i++)
//	{
//	num[i]=i;
//	printf("add task %d\n",i);
//	threadpool_add(thp,process,(void*)&num[i]);
//	}
//	sleep(10);
//	threadpool_destroy(thp);
//}